Method and apparatus for smelting and casting metals or the like



Dec. 18, 1962 A. LINDNER 3,068,538

METHOD AND APPARATUS FOR SMELTING AND CASTING METALS OR THE LIKE FiledMarch 11, 1957 3 SheetsSheet l W M AGEN? Dec. 18, A. LINDNER METHOD ANDAPPARATUS FOR SMELTING AND CASTING METALS OR THE LIKE Filed March 11,1957 3 Sheets-Sheet 2 INVENTOR. A RA/O L //V0/VR AGE/V7 nmEmm i Dec. 18,1962 A. LINDNER METHOD AND APPARATUS FOR SMELTING AND CASTING METALS ORTHE LIKE 3 SheetsSheet 3 Filed March 11, 1957 INVEN TOR.

A RNO .4 lNO/VER vllllllllllllllllllllll llllllllllllllllll' Byway g3,068,533 METHQD AND APPARATUS FQR SMELTRNG AND CASTKNG METALS OR THELIKE Arno Lindner, Diefenbachstrasse 11, Munich-Satin, Germany FiledMar. 11, 1957, Ser. No. 645,231

Claims priority, application Germany Mar. 12, 1956 6 Claims. (Cl. 22-65)The present invention relates to a method and apparatus for smelting andcasting of metals and other materials such as used in dental and jewelrywork and contemplates the use of a furnace or smelting apparatus whichis combined with a casting mold.

More in particular the invention is concerned with a method andapparatus whereby the smelting apparatus is first moved about an axis ofrotation while in upright position and is then placed into a slanted orhorizontal position for casting.

it is an object of the invention to render the charge first into amolten condition while the smelting device containing the crucible is inupright position where it can be subjected to proper observation. Thenthe apparatus is moved about the axis of rotation while in an uprightposition and is finally brought into an inclined or horizontal positionby a tilting or rocking movement after the centrifugal forces involvedhave reached the conditions which safeguard the proper performance ofthe casting process.

This type of working procedure insures that the form can be completelyfilled preparatory to the casting operation and that the forces whichdevelop are not excessive. It is possible to achieve this in accordancewith a further object of the invention in that the smelting device issubjected, for the actual casting, to a brake controlled tiltingmovement.

It is known to cast metals or steels in centrifugal casting operationsby using a crucible which is combined with a mold and is rotatablyarranged about an axis of rotation. Casting arrangements of this typeare used especially in laboratory work for molding fine or preciousmetals. In a casting apparatus of this type known heretofore, thefurnace or crucible was arranged together with the mold in horizontalposition upon an arm of the axis 7 of rotation and the casting proceededin such a manner that the charge in the crucible was first brought tothe required temperature by electric heating and then the crucible andmold were turned by means of a spring driven mechanism about the axis ofrotation so that the charge in the crucible was cast under the effect ofthe centrifugal force into the mold. This known manner of operation hadthe disadvantage that the charge could not be sufiiciently observedduring the smelting operation and besides the casting step proper duringits course and the attendant forces applied during its performance werenot completely under control.

The method in accordance with the invention is advantageously carriedout in such a manner that the current supply to the furnace ismaintained until completion of the centrifugal casting step. In thismanner it is avoided that the melted charge loses heat prior to thecasting op eration and during the casting operation, which might resultin defective casts. This is particularly of importance in connectionwith metals, alloys and other materials which it is difficult to castand which have a high melting point such as silicates. The initiationand release of the tilting movement of the smelting device from thevertical position into an inclined or horizontal position is hereadvantageously effected by centrifugal force while using mechanical,electrical, hydraulic or pneumatic means. This insures that the tiltingoperation is first initiated 3,%8,538 Patented Dec. 18, 1 962 ice afterthe rotating tilting device and the charge in the crucible have attainedsuilicient potential energy from the centrifugal effects applied theretoand when the path for the charge into the casting form is opened by thetilting of the smelting device.

In accordance with further objects of the invention differentembodiments of the structural details of apparatus are provided forcarrying out the method on which the invention is based. The inventionrelies in the first place on such a known centrifugal machine where asmelting device combined with a mold is arranged for rotation around anaxis and the invention provides for constructing the smelting device andcasting form for tilting toward the axis of rotation. For this purpose,the smelting device can be arranged advantageously upon a tilting axlewhich is suitably provided with a release device which normally preventsa tilting movement of the smelting device. The release device isfurthermore suitably restrained by a control device which, depending onthe centrifugal force, operates the release mechanism and thus frees thesmelting device for the tilting movement. The course of the tiltingmovement and its speed can be controlled by an adjustable braking devicewhich is preferably a hydraulic means.

In accordance with the invention, the furnace of the smelting device ismade in the form of a transformer heater in which a carbon heater tubeor a crucible of graphite carbon or other electrically conductive metalis connected in an electric circuit particularly into the secondarycircuit of a transformer. The contacts of the heater are resilientlysupported in accordance with the invention while the current supply tothe contacts of the furnace is effected by way of movable leads. Themethod and the arrangement in accordance with the invention areparticularly of importance for metals and steel or steel alloys andmetal alloys as well as silicates which have a high melting point,particularly in the range of temperatures from 2600 to 3000 C. Fortemperatures above 1500 C. it is suitable to use a crucible of corundumor magnesium oxide.

Further advantages, objects and details of the invention will becomeapparent from the drawing in which the invention is illustrated inconnection with one embodiment and where,

FIG. 1 is a plan view of the apparatus showing one embodiment of theinvention.

FIG. 2 is a side elevation showing the apparatus with the casting devicein tilted position, and

PEG. 3 is a cross section taken on an enlarged scale along line I*I-IIin FIG. 1.

A turntable 2 is arranged for rotation about an axle 1 above a housing 3in which a transformer for supplying the current to the crucible ismounted and a transmission for driving the turntable 2. Two standards 4are secured upon turntable 2 proximate the outer border in which thepivotal support or tilting axle 5 of the crucible 6 is journaled. Thefurnace 6 may be constituted of an outer insulating shell in theinterior of which a carbon heater tube 7 is provided between the uppercontact head 8 and the lower contact head 9 and which surrounds aceramic crucible iii. The contact heads 8 and 9 are preferably made ofred brass or bronze and the lower contact ll and the upper carboncontact 12 are received therein and are adjustably mounted upon commonstandards 13 presenting ratchet teeth 13a for example by means of springbiased catch bolts 35 adapted to engage teeth 13a, and are elasticallysupported by springs 14 which, among other things, prevent that thecarbon heater tube 7' is strained too much if the contact head 8 isplaced under tension. Above contact head 8 a mold box 15 is provided,the mold cavity of which communicates with the interior of the crucibleland which is secured upon standard 13 by means of cross head 16. Thepivotal support or tilting axle 5 is provided with a downwardlyextending hook 17 which is engaged by the detent 13 which is constitutedessentially by a plunger which is movable against the spring 19 andwhich engages the hook 17 with its upper end in such a manner that thetilting axle 5 is retained in a position which corresponds to theupright position of the crucible 6.

A set screw 2% engages the detent 18 which is connected to a weight 22by way of a movable axle 21.

As the disc 2 is rotated the centrifugal force acts upon weight 22 whichbecomes so great upon attaining a pre-determined adjustable number ofrotations that the detent 18 is shifted downwardly thus releasing thehook 17.

As shown in FIGS. 1 and 2 the tilting axle or pivotal support 5 may beextended at one of the outer sides and provided with a lever joint 23which is engaged by the piston rod 24 of a hydraulic brake cylinder 25,the resistance of which is adjustable by the operation of the throttlebolt 26 which, by more or less deeper insertion changes the crosssection of the channel 27 leading from one side of the piston to theother in the cylinder 25.

A counter weight 28 is arranged to be radially movable upon theturntable 2.

A special intermediate member 29 for extending the length of thecrucible It} is shown in FIG. 3. As shown in FIG. 2 a transformer 3% isarranged inside the housing 3 besides the driving means for disc. 2 aswell as the current contacts and the brushes 31 which rest upon sliprings 32. Current conductor bars 33 and movable current supply leads 34are provided which conduct the current from the transformer 39 by way ofbrushes 31 and slip rings 32 to the contact heads 8 and 9.

The method of operation in accordance with the invention can be effectedwith the illustrated embodiment as follows:

With the smelting furnace in upright position the cru cible It} togetherwith the charge is moved into the furnace and the contact heads 8 and 9are connected 7 of the charge is obtained the mold box is placed on topand is secured thereon by means of the cross head 7 16 and the turntable2 is started to rotate by means of the motor. Upon attaining sufiicientperipheral speed the lever 22 is operated by centrifugal force so thatthe catch 18 is pressed downwardly and releases the arm or hook 17 andthe furnace 6 together with the mold box 15 is enabled to tilt intohorizontal position. Under the influence of the centrifugal force thecharge in the crucible 10 now shoots into the cavity of the mold box 15and fills the same in the desired manner. a

The course and the velocity of the tilting movement retarded by means ofthe brake cylinder and this to an extent which can be accuratelycontrolled by means of the adjusting screw 26; Upon completion of thecast-.

ing, turntable 2 is stopped, the furnace 6, together with the mold box15 is tilted upwardly and the parts are separated from one another. 7

The invention is not limited to the embodiment described andillustratedand is not restricted to the struc tural details of thedrawing. For example, it is possible to use a carbon or graphitecrucible in lieuof the carbon heater tube 7." Furthermore, the releaseof the tilting smelting device by hydraulic or pneumatic means. Also thebraking of the tilting movement upon initiation of the tilting operationmay be effected by hydraulic means or with pneumatic or electrical ormechanical means.

Dividing the crucible into an actual crucible portion 10 and anintermediate member 29 serves the important purpose of interceptingthermal stresses in the dense ceramic material of the crucible and thuspreventing destruction of the crucible wall by such thermal stresses.

Having now described my invention with reference to the embodimentsillustrated in the drawings I do not wish to be limited thereto, butwhat I desire to protect by Letters Patent is set forth in the appendedclaims.

I claim:

1. Method of centrifugally casting metals or other smeltable materialswhere the charge is cast by centrifugal force from a smelting deviceinto a casting mold, said method comprising the steps of smelting acharge of material in the smelting device by supplying electric currentthereto, rotating the smelting device together with the casting mold inupright position along a circular path about an axis of rotation whilesupporting the mold above said smelting device, tilting said device andsaid mold outwardly for casting the molten charge under centrifugalforce into the mold, and checking the tilting movement of said deviceand said mold by a braking action.

2. Method of centrifugally casting metals or other smeltable materialswhere the charge is cast by centrifugal force from a smelting deviceinto a casting mold, said method comprising the steps of smelting acharge of material in the smelting device by supplying electric currentthereto, rotating the smelting device together with the casting mold inupright position along a circular path about an axis of rotation Whilesupporting the mold above said smelting device, tilting said device andsaid mold outwardly for casting the molten charge under centrifugalforce into the mold, continuing the supply of current to said deviceduring tilting and checking the tilting movement of said device and saidmold by a braking action.

3. A casting apparatus comprising a turntable in the form of a diskpresenting a flat uppersurface area and including a motor meanstherefor, a smelting furnace and a casting box disposed ininvertedposition on top of.

said smelting furnace and'connected therewith, said furnace and saidcasting box being pivotally supported in upright position on saidturntable for centrifugally induced tilting movement downwardly andoutwardly. and means associated with said turntable adapted to controlthe tilting movement of said furnace and said casting box in a manner totilt said furnace and said casting box into horizontal position uponheating and melting the charge in said furnace.

7 former being connected to supply power to said furnace -by way ofsliding contact means including brushes and slip rings associated withsaid turntable and conductor means connected to saidfslip rings, saidfurnace supmovement of the furnace 6 need not. be effected me-'chanically but can also take place in any other desired manner, forexample, by electro-magnetic means. It

is also possible to carry out the initiation or release of the tiltingmovement ofthe'cmcible or of the entire porting means comprisingsupporting standards on said turntable and a til-ting axle .carryingsaid furnace and said casting box and said turntable having a centralshaft supporting said slip rings adjacent. said brushes,

said apparatus further comprising a detent mechanism in operativeengagementwith a member of said furnace supporting means normallyrestraining said furnace and box against tilting and a release device inoperative engagement with said detent including centrifu gally operatedmeans adapted to release said detent upon imparting thereto apredetermined centrifugal force.

5. A casting apparatus comprising in combination a turntable in the formof a disk presenting a flat upper surface area and including a motivemeans therefore, a smelting furnace and a casting box disposed ininverted position on top of said smelting furnace and connectedtherewith, said furnace and said casting box being mounted upright onsaid turntable for tilting movement outwardly and supporting meanstiltably supporting said furnace and said casting box on said turntable;said motive means comprising an electric motor and a transformer beingconnected to supply power to said furnace by way of sliding contactmeans including brushes and slip rings associated with said turntableand conductor means connected to said slip rings, said furnacesupporting means comprising supporting standards on said turntable and atilting axle carrying said furnace and said casting box and saidturntable having a central shaft supporting said slip rings adjacentsaid brushes, said apparatus further comprising a detent mechanism inoperative engagement with a member of said furnace supporting meansnormally restraining said furnace and box against tilting and a releasedevice in operative engagement with said detent including centrifugallyoperated means adapted to release said detent upon imparting thereto apredetermined centrifugal force and an adjustable braking means adaptedto check the tilting movement of said furnace and said casting box.

6. A casting apparatus comprising in combination a turntable in the formof a disk presenting a flat upper surface area and including a motivemeans therefor, a smelting furnace and a casting box disposed ininverted position on top of said smelting furnace and connectedtherewith, said furnace and said casting box being mounted upright onsaid turntable for tilting movement outwardly and supporting meanstiltably supporting said furnace and said casting box on said turntable;said motive means comprising an electric motor and a transformer beingconnected to supply power to said furnace by Way of sliding contactmeans including brushes and slip rings associated with said turntableand conductor means connected to said slip rings, said furnacesupporting means comprising supporting standards on said turntable and atilting axle carrying said furnace and said casting box and saidturntable having a central shaft supporting said slip rings adjacentsaid brushes, said apparatus further comprising a detent mechanism inoperative engagement with a member of said furnace supporting meansnormally restraining said furnace and box against tilting and a releasedevice in operative engagement with said detent including centrifugallyoperated means adapted to release said detent upon imparting thereto apredetermined centrifugal force, and an adjustable braking means adaptedto check the tilting movement of said furnace and said casting box, saidbraking means comprising a hydraulic cylinder and piston operativelyconnected to said axle.

References Cited in the file of this patent UNITED STATES PATENTS1,823,037 Fritzsche Sept. 15, 1931 2,037,618 Carpenter Apr. 14, 19362,104,380 Touceda Jan. 4, 1938 I FOREIGN PATENTS 412,802 Great BritainSept. 12, 1933

